On Mon, Jan 14, 2019 at 9:22 PM Akira Yokosawa <akiyks@xxxxxxxxx> wrote:
>
> Hi Junchang,
>
> On 2019/01/14 18:31:21 +0800, Junchang Wang wrote:
> > FCV_SNIPPET" blocks are used to hide
> > code for debugging
> >
> > On Mon, Jan 14, 2019 at 7:31 AM Akira Yokosawa <akiyks@xxxxxxxxx> wrote:
> >>
> >> From 1ffe7edfb90cbb8efb2a33d2ae8c3e855e684acf Mon Sep 17 00:00:00 2001
> >> From: Akira Yokosawa <akiyks@xxxxxxxxx>
> >> Date: Sun, 13 Jan 2019 19:47:23 +0900
> >> Subject: [PATCH 1/6] datastruct/hash: Simplify hash_resize.c
> >>
> >> By keeping updating the current (old) hash table until resizing
> >> completes, hashtab_lookup() only needs to see the current hash table.
> >> Instead, hashtab_add() and hashtab_del() need to update the bucket in
> >> the current hash table as well as that in the new hash table if
> >> hashtab_lock_mod() has locked the new bucket.
> >>
> >> This simplifies the lookup side and no performance degradation
> >> is expected as long as no resizing is in progress.
> >>
> >> Note that during resize operation, the cost of updates can be
> >> doubled in the worst case.
> >>
> >> Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
> >> ---
> >> CodeSamples/datastruct/hash/hash_resize.c | 56 ++++++++++++++-----------
> >> CodeSamples/datastruct/hash/hashtorture.h | 6 ++-
> >> datastruct/datastruct.tex | 69 ++++++++++---------------------
> >> 3 files changed, 59 insertions(+), 72 deletions(-)
> >>
> >> diff --git a/CodeSamples/datastruct/hash/hash_resize.c b/CodeSamples/datastruct/hash/hash_resize.c
> >> index 9f9fe8c..e475910 100644
> >> --- a/CodeSamples/datastruct/hash/hash_resize.c
> >> +++ b/CodeSamples/datastruct/hash/hash_resize.c
> >> @@ -30,7 +30,9 @@
> >> struct ht_elem {
> >> struct rcu_head rh;
> >> struct cds_list_head hte_next[2]; //\lnlbl{ht_elem:next}
> >> - unsigned long hte_hash;
> >> +#ifndef FCV_SNIPPET
> >> + unsigned long hte_hash[2];
> >> +#endif /* #ifndef FCV_SNIPPET */
> >
> > Hi Akira,
> >
> > I understand that the micro FCV_SNIPPET is used to hide code for
> > checking hash value in this patch set. I just curious about the exact
> > meaning of the term FCV_SNIPPET itself. Specifically, what does the
> > acronym FCV stand for? I encountered it multiple times while checking
> > the code of perfbook, but didn't find any documentation.
>
> Brief documentation is given in the header of utilities/fcvextract.pl.
> "FCV" came from a LaTeX package name "fancyvrb".
> The macro FCV_SNIPPET is not supposed to be actually defined.
> In this particular case, defining it can eliminate the code
> to check hash values.
>
> Does this short answer make sense to you?
>
Hi Akira,
Yes, it's pretty clear; now I know where the term FCV comes from. :-)
Thanks a lot.
--Junchang
> To add explanation of FCV_SNIPPET and other new features of
> fcvextract.pl in the style guide is on my to-do list.
>
> Thanks, Akira
>
> >
> > Thanks,
> > --Junchang
> >
> >
> [...]
